WSUS Server Randomly Disconnects After Running for a While

Your WSUS Server starts to randomly disconnect after running for a while, and a reboot of the server usually fix the issues, but later on, the issue will return and will require another reboot to remedy.

The error will look like this:

Oddly enough the problem can have to do with WSUS hitting a memory usage limit established by its IIS Application Pool.

Open up IIS, click on Application Pools,  and look at the Status of the WSUSPool (it will likely be Stopped)

Right click on the WsusPool and click on Advanced Settings...

In the Advanced Settings Window, scroll down until you see the field labeled Private Memory Limit (KB)  You can use a KB - GB Calculator like this one to calculate your value back down to KB from GB.  You will notice that in your case the number will most likely be set to something like 1887436 (roughly 1.8GB).  This means that once WSUS uses 1.8GB of RAM, IIS will shut it down (which is why a reboot will usually fix the problem for a while).

In the screenshot above, I've adjusted my WSUS server to be able to use a Maximum of 5GB of RAM at a time before IIS shuts it down.  You can adjust this to suit your environment of course.

I made this change and gave WSUS a reboot, and the Application Pool issue has not returned yet.

Hopefully, that was helpful!